Implement correct orthographic projection #22985
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sbaranov
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sbaranov
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sbaranov
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| final Matrix4 transform = getTransformTo(ancestor); | ||
| final double det = transform.invert(); | ||
| if (det == 0.0) | ||
| return Offset.zero; | ||
| return MatrixUtils.transformPoint(transform, point); |
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should transformPoint itself be fixed?
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It looks like transformPoint is used by some code that doesn't expect unprojection (see localToGlobal). So we would probably keep transformPoint as is, and create new function perspectiveTransformPoint. We could do this change incrementally if people find more problems with various hit testing.
| final Vector3 o = Vector3(0.0, 0.0, 0.0); | ||
| final Vector3 n = Vector3(0.0, 0.0, 1.0); | ||
| final Vector3 p = s + d * (n.dot(o - s) / n.dot(d)); | ||
| return Offset(p.x, p.y); |
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What's the likely performance impact of this change? (This code is potentially hot in certain cases.)
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I went ahead and optimized it slightly, but it shouldn't be bad either way since it's still relatively light weight (only four divisions) and is only called O(1) times per frame. It could be optimized further, but likely not worth it.
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Consider updating https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/painting/matrix_utils.dart#L122 instead (or add an explanation there saying why it's different). Assuming the performance implications aren't dire, LGTM modulo suggested changes. |
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Doc comment updated to explain that. |
This fixes gestures in InkWell and WebView (#6080).